Mobile devices with multiple processing components dedicated to separate tasks are becoming increasingly common. For example, mobile phones often contain a baseband processor dedicated to handling the connection and disconnection of calls, and a separate media processor dedicated to displaying a user interface and receiving requests from a user. Such components may share a volatile main memory for use during operation, or each component may have a dedicated memory. Each component may have its own nonvolatile memory used to store startup logic and configuration data. In addition, each component may have its own proprietary interface for communication with the other components.
The cost of manufacturing a device is directly related to the number of components included within the device. Therefore, it is a common manufacturing goal to reduce or eliminate redundant components to save money. Additional components also increase the power consumption of the device, which directly affects the battery life of mobile devices. Therefore, reducing components also prolongs battery life. In addition, the number of buses and other interfaces between components increases the complexity of a device. Increased complexity contributes to the difficulty of designing and testing the device and increases the time required to bring a new product to market.
One component that can be particularly costly in a device is the nonvolatile memory used to initialize the device. Typically an EEPROM is used that can be flashed with startup logic and configuration data at the factory, sometimes referred to as flash memory. Flash memory is available in two types, NAND and NOR, referring to the predominant type of logic gates used within the flash memory for storing data. NOR flash memory is fast, having microsecond access times, while NAND flash memory is slower, typically having millisecond access times. However, this speed comes with a price, and NOR flash memory is more expensive than NAND flash memory. Device manufacturers must make a trade-off between the speed of the flash memory and its cost. Consumers typically expect fast startup times for consumer electronic devices (e.g., cellular phones and DVD players) tipping the balance in favor of using a faster flash memory, so the flash memory is often one of the more expensive components of a device. When multiple processing components are included within a device, each having its own flash memory, the cost can be substantial.